[CROS34]

I am sorry if I don’t formulate this question correctly as I am a novice when comes to engines, but I read in the past that Pontiac blocks such as the 400, 428, 455, as well as others, are all cast the same, just machined differently? If true are all the holes, tapped or otherwise, the same or were the blocks only cast the same per year? How about the stamping for say a ’70 400 block with WT, YS, etc…. Are these stamping just to show how the motor was set up and for what transmission it was mated to as well as year and such? I guess my main question is, if you had a motor from say ’68 to ’75, would all the parts and pieces from a ’77 or ’78 bolt on?

[Skip Fix]

Early block will need 5 hole drilled for early and late model. The later mounts are 3 bolts some of the early are just 2 hole . I have a '70 455 in my 78 TA